The present invention relates to a starter for an internal combustion engine and, in particular, to a starter wherein fluctuations in the force required to pull the starter rope can be minimized, thereby enabling the starter rope to be smoothly pulled and providing excellent performance of the starter. Specifically, the present invention relates to a power-accumulation type starter wherein the rotational force of the starter is accumulated by means of a spiral spring for starting an internal combustion engine.
In some conventional manual starters for an internal combustion engine, the starting of the internal combustion engine is performed through a process wherein the starter rope is pulled to rotate the rope pulley, and the rotation of the rope pulley is directly transmitted to the crank shaft of the engine so as to start the engine. There is also known a starter wherein a decompressor is employed with a view to minimizing the force for pulling a starter rope handle.
There is also known, as another type of conventional starter for internal combustion engines, a power-accumulation type starter wherein a spiral spring is manually wound up so as to accumulate the rotational force, and the power thus accumulated is then released all at once. According to the conventional starter, a pulley is rotated by pulling a starter rope by means of the starter rope handle, and the rotational force of the pulley is accumulated in the spiral spring, the rotational force being subsequently transmitted to the crank shaft of the internal combustion engine through an actuating pulley so as to start the engine.
The conventional starter constructed as described above is, however, accompanied with a problem in that the starter rope handle for pulling the starter rope is required to be pulled at a relatively high speed and for a long distance, so that it is difficult for a person having weak physical strength to easily start the engine. Moreover, since the rope handle-pulling operation is accompanied with a large fluctuation in the pulling force due to the load to be imposed by the internal combustion engine side in accordance with the rotation of the crank shaft, it is difficult to perform a smooth pulling operation. Hence, it is difficult for a person having weak physical strength to easily start the engine. When a decompressor is employed for the purpose of alleviating the pulling force, an unburned air-fuel mixture is allowed to be released to the external atmosphere, thus causing environmental problems.
On the other hand, a starter having a mechanism wherein the actuating pulley is arranged to be automatically rotated as the rotational force is accumulated up to a predetermined degree is accompanied with problems that the structure thereof becomes complicated, thus making the starter larger in size and weight, and hence unsuitable for use in a small working machine.
The present invention has been made to solve the aforementioned problems. Therefore, it is an object of the present invention to provide a starter which is capable of minimizing fluctuations in the pulling force of the rope handle so as to make it possible to perform a smooth pulling operation and so that the starter can be easily manipulated even by a person having weak physical strength in starting the engine. Another object of the present invention to provide a starter which is excellent in its performance in starting an internal combustion engine and free from environmental problems.
A further object of the present invention is to provide a power-accumulation type starter which, in contrast to the conventional recoiling rope type starter, is capable of easily and reliably starting the engine, irrespective of the pulling speed as well as pulling distance of the starter rope by means of the rope handle, while allowing the starter to be employed in the same manner as the conventional recoil starter by canceling a power accumulation mechanism if the accumulation of rotational force is not required.
A further object of the present invention is to provide a power-accumulation type starter that is simple in construction and light in weight, thereby making it suited for use in a small working machine, that can be easily operated to start the engine while a machine equipped with an internal combustion engine having the starter of the present invention is carried on an operator""s back by locating a rope handle and a start reset lever near the operator""s hands. In addition, if accumulation of rotational force in a spring is not required to start the engine, the starter of the present invention can be used as a recoil type starter having a mechanism for buffering the load to be imposed thereon from the engine side.
With a view to attaining the aforementioned objects, there is provided, in accordance with the present invention, a starter comprising a driving section, a driven section, and a buffering/power-accumulating device interposed between the driving section and the driven section. The buffering/power-accumulating device is enabled, during the driving process of the driving section, to buffer a load from an engine side and to accumulate the power supplied by the driving of the driving section, and the driven section is arranged to be actuated by the accumulated power.
With the starter of the present invention having the aforementioned structure, since the buffering/power-accumulating device is interposed between the starter rope constituting the driving section and the crank shaft of the internal combustion engine constituting the driven section, all of the force for pulling the starter rope is not directly related to the starting of the engine, but part of the pulling force of the starter rope is accumulated in the spiral spring mechanism in an initial part of the process of recoiling, and the accumulated pulling force is afterward combined with the actual pulling force of the starter rope in a later part of the process of recoiling, thereby presenting a resultant force to start the engine. Therefore, even if the force for pulling the starter rope is weak, the engine can be reliably started. In particular, the buffering/power-accumulating device is capable of not only functioning to buffer and accumulate the pulling force of the starter rope but also providing an additional force for starting the engine by releasing the power accumulated therein.
In a preferred embodiment of the present invention, the driving section comprises a reel, and the driven section comprises an interlocking pulley provided with a transmission mechanism through which the interlocking pulley is linked to the driving section. The buffering/power-accumulating device may be constituted by a spiral spring mechanism in which a spiral spring is interposed between a spiral spring box disposed on the driving section side and an actuating pulley disposed on the driven section side. An input device is provided to unidirectionally rotate the spiral spring box. In a preferred embodiment of the present invention, the input device for unidirectionally rotating the spiral spring box includes a one-way clutch, and the transmission mechanism is a centrifugal clutch which is constituted by engaging projections and start-up claws pivotally supported by the interlocking pulley so as to engage with the engaging projections, thereby enabling the rotation of the reel to be transmitted through the spiral spring mechanism to the interlocking pulley linked with the crank shaft of the internal combustion engine.
According to the starter constructed as described above and representing one embodiment of the present invention, the reel is manually rotated by a starter rope wound onto a starter pulley, and the resultant rotational force is once transmitted to the spiral spring mechanism before it is utilized for the rotation of the actuating pulley, so that the fluctuating load due to the working strokes of the internal combustion engine can be absorbed by the spiral spring mechanism, thereby making it possible to smoothly pull the rope handle. Therefore, the internal combustion engine can be easily started by even a person who has weak physical strength. Further, since the crank shaft is rotated through the spiral spring mechanism, the internal combustion engine can be started always with an optimum timing in terms of starting conditions, and the performance of the starter can be improved. Also, since the spiral spring mechanism is enabled to unidirectionally rotate by making use of the one-way clutch, the starter can be reliably operated and also can be made small in size.
A power-accumulation type starter, according to some embodiments of the present invention, has a spiral spring power-accumulating mechanism, a manual reel for accumulating a rotational force in the spiral spring power-accumulating mechanism, a reset lever having a stopper for stopping the rotation of the output side of the spiral spring power-accumulating mechanism to thereby retain the rotational force accumulated until a predetermined torque is reached, and a transmitting mechanism for transmitting an accumulated rotational force to a crank shaft of an internal combustion engine when the stopper is released from stopping the rotation of the output side.
In a preferred embodiment of the power-accumulation type starter according to the present invention, the reset lever is movable between a stop position and a free position by means of an instantaneous switching mechanism, and the instantaneous switching mechanism is provided with a spring member which is interposed between an anchoring portion and the reset lever.
In a preferred embodiment of the power-accumulation type starter according to the present invention, the spiral spring power-accumulating mechanism is featured in that it is constituted by a spiral spring which is interposed between a spiral spring box disposed on the input side and an actuating pulley disposed on the output side, that a rope groove for winding a rope is formed on an outer periphery of the manual reel, and that the spiral spring power-accumulating mechanism and the manual reel are coaxially mounted, and the reset lever is enabled to be manually moved from the stop position to the free position.
With the power accumulation type starter of the present invention that is constructed as described above, the rotational force can be effectively accumulated in the spiral spring power-accumulating mechanism even if the speed with which the rope handle is pulled is slow and even if:the pulling distance is short. Further, since the rotational force is transmitted to the crank shaft so as to start the engine in a state where the torque of the rotational force becomes sufficiently high, the engine can be very easily started. Additionally, when the stopper is arranged to be instantaneously released from stopping the power-accumulating mechanism at the moment when the rotational force of the actuating pulley has reached a predetermined value of torque, the engine can be reliably started. Furthermore, since a decompressor for facilitating the starting operation is not required to be used, there will be no environmental problem resulting from the release of the unburned air-fuel mixture.
Since the instantaneous switching mechanism according to the present invention is provided with a spring member which is interposed between the fixed portion of the switching mechanism and the reset lever, the construction thereof can be simplified and the operation thereof can be reliably performed. Further, since the spiral spring power-accumulating mechanism and the manual reel are coaxially mounted, the construction of the instantaneous switching mechanism can be simplified and kept small in size. Further, the power-accumulation type starter can be used as an ordinary recoil starter without making use of the spiral spring power-accumulating mechanism. In this case, the spiral spring will function as a buffering member, thereby making it possible to alleviate an increased load resulting from the compression stroke of the internal combustion engine.